Fuel oil blending to improve pour reduction

ABSTRACT

A low pour point fuel oil blend is prepared from a major amount of a high pour point, low sulfur, waxy, residual fuel and a minor amount of low-waxy, low pour, residual fuel oil by adding thereto from 0.01 to 0.5 percent by weight of an oil soluble ethylenevinyl fatty acid ester copolymer in which the fatty acid component of the ester has a carbon content of from about 2 to about 6; the copolymer having a molecular weight between about 20,000 and 31,000, a melt index of about 5 to about 28 and a vinyl fatty acid ester content of from about 24 to about 34 percent. The copolymer may be added either in a water-glycol emulsion or in a hydrocarbon to one of the blend components which has been heated to between about 200* to 400*F.

United States Patent [191 v Cole et al.

[ FUEL OIL BLENDING TO IMPROVE POUR I REDUCTION p [75] Inventors: EdmundW. Cole, Poughkeepsie;

Jerzy J. Bialy, Lagrangeville; William M. Sweeney, Wappingers Falls, allof N.Y.

[73] Assignee: Texaco Inc., New York, N.Y.

[22] Filed: June 25, 1970 [21] Appl. No.: 49,991

Related US. Application Data [63] Continuation-impart of Ser. No.878,919, Nov. 21,

. 1969, abandoned.

[52] US. Cl. 44/62, 44/70 [51] Int. Cl C101 1/18 [58] Field of Search44/62, 70; 252/56 [56 References Cited UNITED STATES PATENTS 2,664,38812/1953 Winterhalter 208/15 X 3,567,639 3/1971 Aaron et al 252/56 Feb.19, 1974 Primary Examiner Daniel E. Wyman Assistant ExaminerY. H.- SmithAttorney, Agent, or FinnThomas H. Whaley; Carl G. Ries 57 ABSTRACT indexof about 5 to about 28 and a vinyl fatty acid' ester content of fromabout 24 to about 34 percent. The copolymer may beadded either in awater-glycol emulsion or in a hydrocarbon to one of the blend componentswhich has been heated to between about 200 to 400F.

6 Claims, No Drawings 1 FUEL OIL BLENDING TO IMPROVE POUR REDUCTIONCROSS-REFERENCE TO CO-PENDlNG APPLICATION This application is acontinuation-in-part application of commonly assigned application Ser.No. 878,919 filed Nov. 21, 1969 now abandoned.

This invention is concerned with means for providing a low sulfur, lowpour fuel oil blend. More particularly, the invention is concerned witha fuel oil blend containing a major amount of a high pour, low sulfur,waxy residual fuel and a minor amount of a low-waxy, low pour residualfuel oil, this blend having a reduced pour point relative to itscomponents owing to the incorporation therein of certain high molecularweight ethylene-vinyl fatty acid ester copolymers.

As is well known, residual fuel oils contain quantities of wax andasphaltic compounds which render them viscous and which sometimesinterfere with practical use thereof. Particularly serious problems canbe encountered in pumping residual fuel oils to a burner and in makingthem flow at low temperatures. Other factors to be reckoned with inregard to these oils are the facts that they behave as non-Newtonianliquids at low temperatures; exhibit variable solidifying temperaturesand manifest peculiar hysteresis phenomena all of which result indifficulties in equipment design.

One approach used in making these oils easier to handle has been tosubject them to fairly lengthy and costly dewaxing procedures.

Another approach which has been suggested and tried in order to bringthe viscosity of residual fuel oils to suitable levels has been todilute or cut them with a major amount of lighter distillate oils. Thisprocedure is expensive because of the considerably higher cost of thedistillate oils relative to that of residual oils.

In recent years it has been recommended to incorporate additives inlubricating oils and in so-called middle distillates in order to tie inthe wax present therein and to improve flow characteristics at reducedtemperatures. The additives in question consist either of compoundsformed by alkylating benzene or naphthalene derivatives; or, ofcopolymers of ethylene-vinyl fatty acid ester of a molecular weight upto 3,000 containing from to 25 percent by weight of the vinyl fatty acidester.

ln commonly assigned, co-pending application, U. S. Ser. No. 832,856,filed June 12, 1969, now abandoned, there has been disclosed and claimeda residual fuel oil composition containing an additive comprising amiddle distillate heating oil boiling from about 350 to 650F and aneffective pour point depressant amount of an oil soluble ethylene-vinylfatty acid ester copolymer or resin in which the fatty acid component ofthe waxy residual fuel oils with low-waxy, low pour residual fuel oilsto give large increases in pour reduction without employing elaboratedewaxing procedures.

An equally important object of the claimed invention is to provide anovel fuel oil blend characterized by a low sulfur content and a reducedpour point resulting from the incorporation therein of a small amount ofcertain ethylene-vinyl fatty acid ester copolymers.

A further object of the claimed invention is to provide a fuel oil blendwhich will be stable at different blend temperatures over storage timesof up to about 3 months.

Other objects of this invention will in part be obvious and in parthereinafter pointed out.

The fuel blend of the invention comprises a major amount (i.e., over 50percent by volume) of a high pour, waxy, residual fuel oil having an APIgravity of about 20.0 to about 25.0; a sulfur content of between about0.40 wt. percent and about 0.96 wt. percent; a

Furol viscosity at 122F of about 60 to about 230; a

flash point of between about 300 and 450F, with a wax content of betweenabout 10 and 20 percent; and a minor amount (i.e., less than 50 percentby volume) of a low-waxy, low pour residual fuel oil having an APIgravity of about 10.0 to about 15.0; a Furol viscosity at 122F of about150 to about 250; a flash point of about 220 to about 350F; a pour pointof between about 25F and about 45F; a wax content of between about 2 and5 weight per cent with a sulfur content of between about 0.50 and about0.90 weight percent. A waxy, low pour residual fuel oil which has givenparticularly good results as the minor constituent of the claimed blendis that known as No. 6 Fuel Oil which has an API gravity of about 12.3,a Furol viscosity of 207.0 at 122F, a pour point of about 40F and a waxcontent of about 3 percent.

The pour point depressant additives suitable in the practice of theinvention comprise oil soluble ethylenevinyl fatty acid ester copolymersin which the fatty component of the ester has a carbon content of fromabout 2 to about 6, the copolymers having an average molecular weight ofabout 20,000 to about 31,000 determined as the Number Average MolecularWeight by the Membrane Osmometry Analytical Method, a vinyl fatty acidester content of from about 24 to about 34 percent and a melt index ofabout 5 to about 28. The preferred copolymers are sold under the tradename of Elvax by the E. l. Du Pont de Nemours Company, the most suitablebeing Elvax 250 which contains 27 to 29 percent of vinyl acetate, has aninherent viscosity at F. of 0.78 dcl./gm. in toluene; a softening pointas d m ne y A-S-Ll L E Z Q llwfiftas d point in paraffin wax of F, aMelt Index of 12-18 and a molecular weight of 23,000 to 27,000. Thematerial is supplied by its manufacturer for use in blends containingwax to provide toughness, flexibility, adhesion and barrier propertiesproperties having nothing common with pour point reduction in fuel oilblends.

basic aliphatic carboxylic acid. The characterization of.

the various Elvax additives is given in Table A below:

TABLE A TABLE 111 Vinyl Acetate 100% Stocks Elvax 250, ELVAX" inCopolymer M lt I d Blended at 350 F .125 .094 .062 .031 F/18 1 93 94 9497 F/18 2 94 94 98 99 F/18 3 97 90 94 94 Louisiana No. 6 37 33 36 40 403942 I 4540 10 In practice the claimed fuel blends suitably are pre- 15032-34 22-23 pared 1n the following manner. Either of the fuel oil 21027-29 335-465 220 2749 25475 components is brought up to a temperatureof between 240 v 27-29 I 22-28 200 and 400F. The pour depressant 1s thenumformly 28 33 3 dispersed in the fuel oil by injecting it into theresiduum 310 24-26 335-465 run downstream in the refinery process area.The comggg 2152 ponent to which the pour depressant has been added is410 174 9 5 3 then thoroughly mixed with the other component of the 46017-19 214-9 blend. Tables IV and V below show the average pour points ofdupliate samples at 0, 3 weeks, 6 weeks and i mm as in d by ASTM 1328difi d 20 3 months. These data show that the blends produced by theinvention desirably remain stable over storage The specific propertiesof the oils used in examples times of a least up to three months. Thedata show also of the practice of the invention appear in Table I below:that lesser quantities of the additives lower the pour TABLE I BASESTOCKS INSPECTION TESTS F/18 F/18 F/18 No.6 Base Stock Fuel Oil (1) FuelOil (2) Fuel Oil (3) Fuel Oil TESTS (iravity, API 22.3 23.5 22.6 12.3Flash Point 425 395 330 270 (COC), "F Viscosity. SUS

at 122F 1043 1971 701 1968 at 15()F 435 404 315 748 ASTM Four 100 100 90Point, F 1 Carbon Residue. 6.8 6.99 6.78 13.61 WTf/v Wax Content, 16.8015.99 12.36 3.05 WTf/r Sulfur. WT/Vr 0.96 0.54 0.84 0.74

It was observed in experimental work leading to the points to a lesserdegree. The data moreover show that present invention that the copolymeradditives did not blending the fuel and additives at 350F. gives aslightly significantly lower the pour points of either of the comsmallerreduction than those blending at 200F. ponents of the blends themselves.Thus addition of TABLE IV 0.125 percent by weight of Elvax 250 to 100percent of the F/18 1 oil) lowers the average pour point Averages ofDuplicate Samples thereof by only 1F. Similarly 0.125 percent by we1ghtF I 3 Weeks. 6 Weeks. 3 Months U8 IXIUTC of the same add1t1ve lowers thepour pomt of the No. 60 (V) F/]8 4o% (v) 6 011 only by about 6 F.Unexpectedly th1s last men- N0. 6 Blended at Elvax 250, tioned amount ofElvax 250 lowers the pour point of a 200 O 60/40 percent by volumemixture of these two oils by (l) N05 80 53 53 76 27. This will be seenin Tables 2 and 3 below. W18 No. 6 a 82 52 57 67 81 F/18 3 N6. 6 79 4447 49 69 TABLE 11 TABLE \1 Averages of Duplicate Samples at 0, 3 weeks,6 weeks, 3 months Fuel Mixture 100% SIOCkH Elvax 250, 60 (v FMS-40% vBlended at 200F 0 .125 .094 .062 .031 No. 6 Blended at Elvax 250,

F/18(1) 92 91 92 94 F/18(2) 98 96 91 91 F/1s 1 -N6.6 83 6O 74 81 F/18(3)96 88 89 91 F/l8(2)-No.6 84 71 73 76 Louisiana No. 6 32 26 29 2s H18 3NO. 6 77 62 70 blend, it will be preferred to dissolve them in ahydrocarbon such as toluene, kerosene, and the like and to emuls'ifywith a mixture of ethylene glycol, water and detergent to form an oil inwater emulsion. The pour point of the resultant emulsion will beessentially that of the water-glycol phase. A practical example of thisapproach is the use of a water-glycol emulsion which contain 22.3percent of the polymer.

On the contrary, where it is desired to use a temperature of around250C. for incorporating the copolymers, it will be preferred to add thecopolymers to the oil at the said temperature in the form of ahydrocarbon solution in, for example, toluene. This can be done bymaking a 12 /2 percent Udex extract hydrocarbon blend incorporating thepolymer.

The unexpected and unobvious nature of the present invention can best beappreciated from the comparison tabulated below in Table VI of the pourpoints obtained with various additives differing in vinyl acetatecontent and melt index. It will be apparent from Table VI that onlycertain additives reduce the pour point while certain others have littleeffect or even increase it. Thus the copolymer Elvax 40 having a percentof vinyl acetate in excess of 34 gave a po'ur point of 80F, a reductionof only 5F from the control and Elvax 460 appeared to increase it by 5F.

TABLE VI Pour Point (F) Elvax No. (0.1% in Blend) FIB/No. 6 FuelBlend 1. Process for producing a low pour point, low sulfur of a lowwaxy, low pour, residual fuel oil, bringing one of said oils to atemperature of between about 200 and 400F.; adding to the said oil apour depressant consisting of an oil soluble, ethylene-vinyl fatty acidester copolymer in which the fatty acid component of the ester has acarbon content of from about two to about six, said copolymer having amolecular weight of about 20,000 to about 31,000, a vinyl fatty acidester content of from about 24 to about 34 percent and a melt index ofabout 5 to about 28; uniformly dispersing said copolymer in said oil atsaid temperature; and mixing said oils to produce a blend having a pourpoint substantially lower than either of said oils.

2. A fuel oil blend characterized by a lowered pour point and a lowsulfur content comprising a major amount of a high pour, waxy, residualfuel oil having a pour point of between about 80 and 120F. and a minoramount of a low waxy, low pour, residual fuel oil and an effective pourdepressant amount of an oil soluble, ethylene-vinyl fatty acid estercopolymer in which the fatty acid component of the ester has a carboncontent of from about two to about six, said copolymer having amolecular weight of between about 20,000 to about 31,000; a vinyl fattyacid ester content of from about 24 to 34 percent, and a melt index ofabout 5 to about 28.

3. The composition according to claim 2 wherein the said vinyl ester isvinyl acetate and wherein the said composition contains over percent byvolume of the said high-pour fuel oil.

4. The composition according to claim 2 wherein said copolymer ispresent in a concentration ranging from about 0.01 to about 0.5 percentby weight.

5. The composition of claim 2 containing 60 percent by volume of saidhigh pour fuel oil and 40 percent by volume of said low pour fuel oil.

6. The composition of claim 2, wherein said high pour, residual fuel oilhas an API gravity ranging between about 20.0 and about 25.0; a sulfurcontent between about 0.40 weight percent and about 0.96 weight percent;a Furol viscosity at 122F. of about 60 to about 230; a flash point ofbetween 300 and 450F. and a wax content of between about 10 and 20percent; said low waxy, low pour residual fuel oil having an API gravityof about 10.0 to about 15.0; a Furol viscosity at 122F. of about 150 toabout 250; a flash point of about 220 to about 350F.; a pour point ofabout 25F. and 45F a wax content of about 2 to about 5 weight perfueloil blend comprising blending a major amount of 50 cent and a sulfurcontent of between about 0.50 and a high pour, waxy residual fuel oilhaving a pour point of between about 80 and l20F.; and a minor amountabout 0.90 weight percent.

2. A fuel oil blend characterized by a lowered pour point and a lowsulfur content comprising a major amount of a high pour, waxy, residualfuel oil having a pour point of between about 80* and 120*F. and a minoramount of a low waxy, low pour, residual fuel oil and an effective pourdepressant amount of an oil soluble, ethylene-vinyl fatty acid estercopolymer in which the fatty acid component of the ester has a carboncontent of from about two to about six, said copolymer having amolecular weight of between about 20,000 to about 31,000; a vinyl fattyacid ester content of from about 24 to 34 percent, and a melt index ofabout 5 to about
 28. 3. The composition according to claim 2 wherein thesaid vinyl ester is vinyl acetate and wherein the said compositioncontains over 50 percent by volume of the said high-pour fuel oil. 4.The composition according to claim 2 wherein said copolymer is presentin a concentration ranging from about 0.01 to about 0.5 percent byweight.
 5. The composition of claim 2 containing 60 percent by volume ofsaid high pour fuel oil and 40 percent by volume of said low pour fueloil.
 6. The composition of claim 2, wherein said high pour, residualfuel oil has an API gravity ranging between about 20.0 and about 25.0; asulfur content between about 0.40 weight percent and about 0.96 weightpercent; a Furol viscosity at 122*F. of about 60 to about 230; a flashpoint of between 300* and 450*F. and a wax content of between about 10and 20 percent; said low waxy, low pour residual fuel oil having an APIgravity of about 10.0 to about 15.0; a Furol viscosity at 122*F. ofabout 150 to about 250; a flash point of about 220 to about 350*F.; apour point of about 25*F. and 45*F.; a wax content of about 2 to about 5weight percent and a sulfur content of between about 0.50 and about 0.90weight percent.